This invention relates to the field of crank gears for cycles and particularly to an assembly including a pedal and a cyclist's shoe having a specially adapted sole.
It is known that to obtain maximum efficiency in crank gears, it is necessary that the pedal toe clip be provided with a strap and the shoe sole be provided with a pedal wedge tthat engages over the back part of the pedal housing. Various embodiments have been proposed to improve the lateral locking positions of the shoe, as for example a pedal with a rear portion having a centrally located cavity (French patent application Nos. 81.17542 and 81.20559).
These improvements, however, have the following disadvantages: (a) the surface of contact between the sole and pedal comprises a very small area of the pedal branches; (b) the tight locking strap of the toe clip is uncomfortable and often dangerous; (c) the shoe cannot be used for walking because of prominence of a pedal wedge under the sole.
It has been proposed to eliminate the toe clip by combining a pedal or pedaling platform having a special structure, as for example lateral slides, with a shoe whose sole is provided either with a female housing element cooperating with a male element on the pedal, or a plate with a projection forming the pedal wedge (see, for example, French Pat. No. 79.04413). However, these systems are complex and use is delicate; further, the device provided under the shoe does not allow normal walking with the latter.